1. Field of the Invention
The present invention relates generally to wireless power transfer, and more specifically wireless power transfer device used for telemetry systems and monitoring devices.
2. Description of the Related Art
Telemetry systems can be implemented to acquire and transmit data from a remote source. Some telemetry systems provide information about a user's activities.
It is becoming commonplace to use wireless packet data service networks for effectuating data sessions with. In some implementations, unique identifications (ID) need to be assigned to the devices in order to facilitate certain aspects of service provisioning, e.g., security, validation and authentication, et cetera. In such scenarios, it becomes imperative that no two devices have the same indicium (i.e., collision). Further, provisioning of such indicia should be flexible so as to maintain the entire pool of indicia to a manageable level while allowing for their widespread use in multiple service environments.
The telemetry system can incorporate a wireless technology such as wireless fidelity (WiFi); infrared (IR); or ultrasound in order to facilitate finding an object and/or data transmission. As an exemplary implementation, a medical telemetry system can be implemented to remotely monitor the cardiac electrical activity of a plurality of ambulatory patients while they remain within a predefined coverage area. The medical telemetry system can also be implemented to locate and track patients within the coverage area.
Wireless electronic devices require typically require their own charger and power source, which is usually an alternating current (AC) power outlet. Such a wired configuration becomes unwieldy when many devices need charging.
Approaches are being developed that use over-the-air or wireless power transmission between a transmitter and a receiver coupled to the electronic device to be charged. Such approaches generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and a receive antenna on the device to be charged. The receive antenna collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas, so charging over reasonable distances (e.g., less than 1 to 2 meters) becomes difficult. Additionally, since the transmitting system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches to wireless energy transmission techniques are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna (plus a rectifying circuit) embedded in the electronic device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g., within millimeters). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically very small and requires the user to accurately locate the devices to a specific area.
Efficiency is of importance in a wireless power transfer system due to the losses occurring in the course of wireless transmission of power. Since wireless power transmission is often less efficient than wired transfer, efficiency is of an even greater concern in a wireless power transfer environment.
There is a need for telemetry systems and monitoring devices with improved wireless communication. There is a further need for telemetry systems and monitoring devices that adapt to changes in coupling between a transmit antenna and a receive antenna to optimize or otherwise adjust power delivery to a receiver device coupled to the receive antenna.